FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_event.c
1 /*-
2 * Copyright (c) 2002 Poul-Henning Kamp
3 * Copyright (c) 2002 Networks Associates Technology, Inc.
4 * All rights reserved.
5 *
6 * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7 * and NAI Labs, the Security Research Division of Network Associates, Inc.
8 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9 * DARPA CHATS research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. The names of the authors may not be used to endorse or promote
20 * products derived from this software without specific prior written
21 * permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /*
37 * XXX: How do we in general know that objects referenced in events
38 * have not been destroyed before we get around to handle the event ?
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/10.4/sys/geom/geom_event.c 266970 2014-06-02 10:14:03Z ae $");
43
44 #include <sys/param.h>
45 #include <sys/malloc.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/mutex.h>
50 #include <sys/proc.h>
51 #include <sys/errno.h>
52 #include <sys/time.h>
53 #include <geom/geom.h>
54 #include <geom/geom_int.h>
55
56 #include <machine/stdarg.h>
57
58 TAILQ_HEAD(event_tailq_head, g_event);
59
60 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
61 static u_int g_pending_events;
62 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
63 static struct mtx g_eventlock;
64 static int g_wither_work;
65
66 #define G_N_EVENTREFS 20
67
68 struct g_event {
69 TAILQ_ENTRY(g_event) events;
70 g_event_t *func;
71 void *arg;
72 int flag;
73 void *ref[G_N_EVENTREFS];
74 };
75
76 #define EV_DONE 0x80000
77 #define EV_WAKEUP 0x40000
78 #define EV_CANCELED 0x20000
79 #define EV_INPROGRESS 0x10000
80
81 void
82 g_waitidle(void)
83 {
84
85 g_topology_assert_not();
86 mtx_assert(&Giant, MA_NOTOWNED);
87
88 mtx_lock(&g_eventlock);
89 while (!TAILQ_EMPTY(&g_events))
90 msleep(&g_pending_events, &g_eventlock, PPAUSE,
91 "g_waitidle", hz/5);
92 mtx_unlock(&g_eventlock);
93 curthread->td_pflags &= ~TDP_GEOM;
94 }
95
96 #if 0
97 void
98 g_waitidlelock(void)
99 {
100
101 g_topology_assert();
102 mtx_lock(&g_eventlock);
103 while (!TAILQ_EMPTY(&g_events)) {
104 g_topology_unlock();
105 msleep(&g_pending_events, &g_eventlock, PPAUSE,
106 "g_waitidlel", hz/5);
107 g_topology_lock();
108 }
109 mtx_unlock(&g_eventlock);
110 }
111 #endif
112
113 struct g_attrchanged_args {
114 struct g_provider *pp;
115 const char *attr;
116 };
117
118 static void
119 g_attr_changed_event(void *arg, int flag)
120 {
121 struct g_attrchanged_args *args;
122 struct g_provider *pp;
123 struct g_consumer *cp;
124 struct g_consumer *next_cp;
125
126 args = arg;
127 pp = args->pp;
128
129 g_topology_assert();
130 if (flag != EV_CANCEL && g_shutdown == 0) {
131
132 /*
133 * Tell all consumers of the change.
134 */
135 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
136 if (cp->geom->attrchanged != NULL)
137 cp->geom->attrchanged(cp, args->attr);
138 }
139 }
140 g_free(args);
141 }
142
143 int
144 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
145 {
146 struct g_attrchanged_args *args;
147 int error;
148
149 args = g_malloc(sizeof *args, flag);
150 if (args == NULL)
151 return (ENOMEM);
152 args->pp = pp;
153 args->attr = attr;
154 error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
155 if (error != 0)
156 g_free(args);
157 return (error);
158 }
159
160 void
161 g_orphan_provider(struct g_provider *pp, int error)
162 {
163
164 /* G_VALID_PROVIDER(pp) We likely lack topology lock */
165 g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
166 pp, pp->name, error);
167 KASSERT(error != 0,
168 ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
169 pp, pp->name));
170
171 pp->error = error;
172 mtx_lock(&g_eventlock);
173 KASSERT(!(pp->flags & G_PF_ORPHAN),
174 ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
175 pp->flags |= G_PF_ORPHAN;
176 TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
177 mtx_unlock(&g_eventlock);
178 wakeup(&g_wait_event);
179 }
180
181 /*
182 * This function is called once on each provider which the event handler
183 * finds on its g_doorstep.
184 */
185
186 static void
187 g_orphan_register(struct g_provider *pp)
188 {
189 struct g_consumer *cp, *cp2;
190 int wf;
191
192 g_topology_assert();
193 G_VALID_PROVIDER(pp);
194 g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
195
196 g_cancel_event(pp);
197
198 wf = pp->flags & G_PF_WITHER;
199 pp->flags &= ~G_PF_WITHER;
200
201 /*
202 * Tell all consumers the bad news.
203 * Don't be surprised if they self-destruct.
204 */
205 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
206 KASSERT(cp->geom->orphan != NULL,
207 ("geom %s has no orphan, class %s",
208 cp->geom->name, cp->geom->class->name));
209 /*
210 * XXX: g_dev_orphan method does deferred destroying
211 * and it is possible, that other event could already
212 * call the orphan method. Check consumer's flags to
213 * do not schedule it twice.
214 */
215 if (cp->flags & G_CF_ORPHAN)
216 continue;
217 cp->flags |= G_CF_ORPHAN;
218 cp->geom->orphan(cp);
219 }
220 if (LIST_EMPTY(&pp->consumers) && wf)
221 g_destroy_provider(pp);
222 else
223 pp->flags |= wf;
224 #ifdef notyet
225 cp = LIST_FIRST(&pp->consumers);
226 if (cp != NULL)
227 return;
228 if (pp->geom->flags & G_GEOM_WITHER)
229 g_destroy_provider(pp);
230 #endif
231 }
232
233 static int
234 one_event(void)
235 {
236 struct g_event *ep;
237 struct g_provider *pp;
238
239 g_topology_assert();
240 mtx_lock(&g_eventlock);
241 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
242 if (pp->nstart == pp->nend)
243 break;
244 }
245 if (pp != NULL) {
246 G_VALID_PROVIDER(pp);
247 TAILQ_REMOVE(&g_doorstep, pp, orphan);
248 mtx_unlock(&g_eventlock);
249 g_orphan_register(pp);
250 return (1);
251 }
252
253 ep = TAILQ_FIRST(&g_events);
254 if (ep == NULL) {
255 wakeup(&g_pending_events);
256 return (0);
257 }
258 if (ep->flag & EV_INPROGRESS) {
259 mtx_unlock(&g_eventlock);
260 return (1);
261 }
262 ep->flag |= EV_INPROGRESS;
263 mtx_unlock(&g_eventlock);
264 g_topology_assert();
265 ep->func(ep->arg, 0);
266 g_topology_assert();
267 mtx_lock(&g_eventlock);
268 TAILQ_REMOVE(&g_events, ep, events);
269 ep->flag &= ~EV_INPROGRESS;
270 if (ep->flag & EV_WAKEUP) {
271 ep->flag |= EV_DONE;
272 mtx_unlock(&g_eventlock);
273 wakeup(ep);
274 } else {
275 mtx_unlock(&g_eventlock);
276 g_free(ep);
277 }
278 return (1);
279 }
280
281 void
282 g_run_events()
283 {
284
285 for (;;) {
286 g_topology_lock();
287 while (one_event())
288 ;
289 mtx_assert(&g_eventlock, MA_OWNED);
290 if (g_wither_work) {
291 g_wither_work = 0;
292 mtx_unlock(&g_eventlock);
293 g_wither_washer();
294 g_topology_unlock();
295 } else {
296 g_topology_unlock();
297 msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
298 "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
299 }
300 }
301 /* NOTREACHED */
302 }
303
304 void
305 g_cancel_event(void *ref)
306 {
307 struct g_event *ep, *epn;
308 struct g_provider *pp;
309 u_int n;
310
311 mtx_lock(&g_eventlock);
312 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
313 if (pp != ref)
314 continue;
315 TAILQ_REMOVE(&g_doorstep, pp, orphan);
316 break;
317 }
318 TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
319 if (ep->flag & EV_INPROGRESS)
320 continue;
321 for (n = 0; n < G_N_EVENTREFS; n++) {
322 if (ep->ref[n] == NULL)
323 break;
324 if (ep->ref[n] != ref)
325 continue;
326 TAILQ_REMOVE(&g_events, ep, events);
327 ep->func(ep->arg, EV_CANCEL);
328 mtx_assert(&g_eventlock, MA_OWNED);
329 if (ep->flag & EV_WAKEUP) {
330 ep->flag |= (EV_DONE|EV_CANCELED);
331 wakeup(ep);
332 } else {
333 g_free(ep);
334 }
335 break;
336 }
337 }
338 if (TAILQ_EMPTY(&g_events))
339 wakeup(&g_pending_events);
340 mtx_unlock(&g_eventlock);
341 }
342
343 static int
344 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
345 {
346 struct g_event *ep;
347 void *p;
348 u_int n;
349
350 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
351 func, arg, flag, wuflag);
352 KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
353 ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
354 ep = g_malloc(sizeof *ep, flag | M_ZERO);
355 if (ep == NULL)
356 return (ENOMEM);
357 ep->flag = wuflag;
358 for (n = 0; n < G_N_EVENTREFS; n++) {
359 p = va_arg(ap, void *);
360 if (p == NULL)
361 break;
362 g_trace(G_T_TOPOLOGY, " ref %p", p);
363 ep->ref[n] = p;
364 }
365 KASSERT(p == NULL, ("Too many references to event"));
366 ep->func = func;
367 ep->arg = arg;
368 mtx_lock(&g_eventlock);
369 TAILQ_INSERT_TAIL(&g_events, ep, events);
370 mtx_unlock(&g_eventlock);
371 wakeup(&g_wait_event);
372 if (epp != NULL)
373 *epp = ep;
374 curthread->td_pflags |= TDP_GEOM;
375 return (0);
376 }
377
378 int
379 g_post_event(g_event_t *func, void *arg, int flag, ...)
380 {
381 va_list ap;
382 int i;
383
384 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
385 ("Wrong flag to g_post_event"));
386 va_start(ap, flag);
387 i = g_post_event_x(func, arg, flag, 0, NULL, ap);
388 va_end(ap);
389 return (i);
390 }
391
392 void
393 g_do_wither()
394 {
395
396 mtx_lock(&g_eventlock);
397 g_wither_work = 1;
398 mtx_unlock(&g_eventlock);
399 wakeup(&g_wait_event);
400 }
401
402 /*
403 * XXX: It might actually be useful to call this function with topology held.
404 * XXX: This would ensure that the event gets created before anything else
405 * XXX: changes. At present all users have a handle on things in some other
406 * XXX: way, so this remains an XXX for now.
407 */
408
409 int
410 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
411 {
412 va_list ap;
413 struct g_event *ep;
414 int error;
415
416 g_topology_assert_not();
417 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
418 ("Wrong flag to g_post_event"));
419 va_start(ap, flag);
420 error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
421 va_end(ap);
422 if (error)
423 return (error);
424
425 mtx_lock(&g_eventlock);
426 while (!(ep->flag & EV_DONE))
427 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
428 if (ep->flag & EV_CANCELED)
429 error = EAGAIN;
430 mtx_unlock(&g_eventlock);
431
432 g_free(ep);
433 return (error);
434 }
435
436 void
437 g_event_init()
438 {
439
440 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
441 }
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